Pressure-sensitive adhesive sheets comprising a substrate, such as a plastic film, paper or cloth, and having provided thereon a soft layer comprising a rubbery polymer or a foamed product thereof which is excellent in softness, fluidity and stress relaxing properties have widely been used as tacky articles having such properties of the soft layer. Depending on the material of the soft layer, those are used as tacky articles which exhibit the above properties even in low temperature, or as inexpensive tacky articles.
The soft layer of this type of tacky articles has bulk physical properties necessary for an adhesive, but pressure-sensitive property of the surface thereof is not yet sufficient. Therefore, in order to obtain sufficient pressure-sensitive property, a pressure-sensitive adhesive layer comprising an acrylic pressure-sensitive adhesive or a rubber pressure-sensitive adhesive is further coated on the surface of the soft layer.
However, if the pressure-sensitive adhesive layer is coated in a thickness of several tens of microns to several millimeters in order to exhibit the desired pressure-sensitive properties, it results in impairing the softness, fluidity and stress relaxing properties, which are advantageous characteristics of the soft layer. On the other hand, if the thickness is decreased to avoid this, the pressure-sensitive adhesive diffuses into the soft layer with the passage of time, decreasing the pressure-sensitive property, or an interlaminar failure occurs between the soft layer and the pressure-sensitive adhesive layer. As a result, a sufficient adhesive strength is not exhibited.